1. Field of the Invention
The present invention relates to a multilayer integrated substrate from which a plurality of multilayer ceramic elements are obtained, and also relates to a method of manufacturing the multilayer ceramic elements by using the multilayer integrated substrate. More specifically, the present invention relates to modifications for increasing the strength of the multilayer integrated substrate that includes breaking grooves for facilitating the process of breaking the multilayer integrated substrate to remove the multilayer ceramic elements.
2. Description of the Related Art
To increase manufacturing efficiency, multilayer ceramic elements such as multilayer ceramic substrates are often prepared in the form of a multilayer integrated substrate, and are obtained from the multilayer integrated substrate by breaking it.
FIG. 10 is a plan view schematically showing a conventional multilayer integrated substrate 1.
The multilayer integrated substrate 1 is obtained by firing a laminate of a plurality of ceramic green sheets so as to have a laminated structure that includes a plurality of ceramic layers.
The multilayer integrated substrate 1 is provided with a plurality of breaking grooves 2 arranged in the main surface in a grid pattern. Desired multilayer ceramic elements 4 are constructed in blocks 3 sectioned by the breaking grooves 3. The multilayer ceramic elements 4 can be then obtained by breaking the multilayer integrated substrate 1 along the breaking grooves 2.
With regard to electronic components mounted in, for example, mobile communication devices, reduction in their heights has been demanded. To satisfy such a demand, the heights of multilayer ceramic elements included in the electronic components must also be reduced.
Accordingly, with reference to FIG. 10, the thickness of the multilayer integrated substrate 1 must be reduced to make the multilayer ceramic elements 4 thinner.
On the other hand, processes such as plating, printing of solder paste, mounting of other electronic components, and other processes, are required for constructing the multilayer ceramic elements 4. In order for all of the multilayer ceramic elements 4 to be processed together at the same time, it is efficient to complete such processes before the multilayer ceramic elements 4 are obtained from the multilayer integrated substrate 1.
When the thickness of the multilayer integrated substrate 1 is reduced as described above, however, undesirable fracturing of the multilayer integrated substrate 1 along the breaking grooves 2 often occurs. Such undesirable fracturing is caused by, for example, pressure or heat applied to the multilayer integrated substrate 1 during the above-described processes such as mounting of components.
In extreme cases, the multilayer integrated substrate 1 may also be fractured due to nonuniform shrinkage in the firing process or thermal shock when the temperature decreases.